The present invention generally relates to power system protection, and more specifically, to a method and apparatus for customization of a protective device.
Electric utility systems or power systems are designed to generate, transmit and distribute electrical energy to loads. In order to accomplish this, power systems generally include a variety of power system elements such as electrical generators, electrical motors, power transformers, power transmission lines, buses and capacitors, to name a few. As a result, power systems must also include protective devices and procedures to protect the power system elements from abnormal conditions such as electrical short circuits, overloads, frequency excursions, voltage fluctuations, and the like.
Protective devices and procedures act to isolate some power system element(s) from the remainder of the power system upon detection of the abnormal condition or a fault in, or related to, the power system element(s). Logically grouped zones of protection, or protection zones utilizing the protective devices and procedures, are established to efficiently manage faults or other abnormal conditions occurring in the power system elements.
Generally, protective devices are also used for protecting, monitoring, controlling, metering and/or automating electric power systems and associated transmission lines. Protective devices may include protective relays, remote terminal units (RTUs), power line communications devices (PLCs), bay controllers, supervisory control and data acquisition (SCADA) systems, general computer systems, meters, and any other comparable devices used for protecting, monitoring, controlling, metering and/or automating electric power systems and their associated transmission lines.
Traditional protective devices generally include various overcurrent, voltage, directional, distance, differential, and frequency protective logic schemes. These logic schemes and the logic elements associated therewith are generally either programmed into user programmable memory or permanently hard coded into fixed memory. Protective devices require flexibility and modification in their processing based on their application in the field. Often, protective device applications are unique in nature. Accordingly, modifications to protective devices used in such applications are similarly unique for a particular user.
In traditional protective devices, some modifications in device processing can be made by the end user (e.g., the customer) by modifying the user programmable memory. For example, the end user may modify the user programmable memory to include custom logic algorithms. Nevertheless, for some complex applications, modification of user programmable memory is insufficient due to inadequate microprocessor capacity or inadequate free volatile memory.
Another traditional approach to modification of protective device processing involves changes in the fixed memory contained permanently in the device. Such fixed memory is alternatively referred to as firmware. Modification of the firmware generally involves changes by the programmer (e.g., the manufacturer) requiring extensive product validation and manufacturing release processes. These validation and release processes are often complicated, costly, and burdensome for both the end user (e.g., customer) and the programmer (e.g., manufacturer).
The cost for modification of firmware in protective devices ranges from a few thousands of dollars, which is rare, to several hundred thousands of dollars, which is more common. Therefore, the manufacturer must weigh whether any increase in sales volume and/or revenue expected from each change would warrant the costs for research, development and implementation of each individual firmware modification. Because modifications are often unique in nature, these costs often do not warrant manufacturer changes for unique applications.
In yet another traditional approach to modification of protective device processing, a separate computing platform may be connected to a protective device in order to control device processing. Nevertheless, traditional operating systems for these computing platforms do not have the capacity to execute device processing within a desired time. For example, the computer is unable to execute device processing within the required operation time for the protective device to execute protection, monitoring, control, metering and/or automation of electric power systems and associated transmission lines (e.g., isolating an abnormal condition in the power system as soon as possible so as to not cause damage within the system). The fast processing time required is generally about 4-5 milliseconds.
Thus, it is an object of this invention to provide a method and apparatus which customizes protective devices for all applications. It is further an object of this invention to provide a method and apparatus for customizing a protective device without modifying the device's firmware.
These and other desired benefits of the preferred embodiments, including combinations of features thereof, of the invention will become apparent from the following description. It will be understood, however, that a process or arrangement could still appropriate the claimed invention without accomplishing each and every one of these desired benefits, including those gleaned from the following description. The appended claims, not these desired benefits, define the subject matter of the invention. Any and all benefits are derived from the multiple embodiments of the invention, not necessarily the invention in general.